Something Strange Occurred 15 Minutes Before the Tonga Eruption: A Signal, Imperceptible to Humans, Traveled Across the Earth’s Surface

It happened in 1912, then again in 1937, 1988, 2009, and 2014. However, 2022 was something entirely different. On Jan. 15, 2022, the Hunga Tonga volcano in the South Pacific erupted in an unprecedented manner, injecting a massive amount of water vapor into the atmosphere at a height of more than 6 miles. This extraordinary event became one of the main factors contributing to the high temperatures recorded in 2022.

Consequences of the eruption. In 2022, the Hunga Tonga-Hunga Ha’apai volcano experienced one of the most powerful eruptions in modern history. The catastrophic event destroyed the island of the same name, blanketed the whole country of Tonga in ash, forced the evacuation of its inhabitants, and resulted in the deaths of dozens of people.

To put the eruption’s magnitude into perspective, the ash column soared to an astonishing height of 36 miles, reaching the mesosphere in just half an hour. What’s more, the Hunga Tonga eruption surpassed even the historic 1991 eruption of Mount Pinatubo in the Philippines, considered the second-largest volcanic eruption of the 20th century.

The “signal.” Recently, scientists from the University of Tokyo made a groundbreaking discovery regarding the 2022 volcanic eruption. They found that a unique seismic signal, called a Rayleigh wave, occurred just 15 minutes before the eruption. Remarkably, this signal had never been detected before and wasn’t perceptible to humans.

The Rayleigh wave was identified by seismometers located in Fiji and Futuna, approximately 460 miles away from the volcano. While this type of surface wave is commonly associated with earthquakes, this marks the first instance where it has been linked to a significant submarine volcanic eruption. This finding provides valuable insights for future volcanic prediction efforts.

The importance of the Rayleigh wave. In their recently published paper, researchers detail how the Rayleigh wave served as a precursor to the eruption and propagated without any visible activity on the surface. This unique characteristic makes it particularly relevant as a potential early warning signal.

This fascinating discovery has prompted researchers to explore the wave’s potential role in enhancing natural disaster prevention systems. They believe that if scientists could monitor the Rayleigh wave in real time, they would be able to anticipate volcanic eruptions, which is crucial for the timely evacuation and protection of at-risk populations.

Mechanism of seismic wave generation. The study concludes that the Rayleigh wave was generated by a fracture in the oceanic crust beneath the volcano. This fracture allowed magma beneath the surface to mix with seawater, destabilizing the volcanic structure.

As pressure increased, the ground above the magma eventually collapsed, triggering a massive eruption. The collapse of the volcanic caldera led to the forceful ejection of magma and gases, resulting in the devastation observed in Tonga.

An unprecedented finding with future implications. The discovery of the Rayleigh wave as a potential indicator of volcanic activity is a significant breakthrough for the field of volcanology. However, there’s one caveat. Currently, no real-time systems are in place that use Rayleigh waves as precursors for eruptions. According to Mie Ichihara, co-author of the study and a volcanologist at the University of Tokyo, developing infrastructure to monitor these waves could enable scientists to detect eruptions before they reach their most destructive stages.

Other detection systems and lessons for the future. The recent study is part of a broader effort to improve warning systems for natural disasters. For instance, in 2021, a team of scientists discovered that tsunamis can be predicted through their magnetic fields, which arrive before changes in sea level. These findings highlight the importance of exploring various methods to detect and anticipate catastrophes, particularly as the world faces an increasing number of extreme weather events.

Researchers also noted that the Tonga eruption could’ve been much more devastating had it occurred in a densely populated area. They hope that the knowledge gained from this unprecedented event will help enhance warning systems and mitigate the impact of future disasters. Moreover, integrating advanced technologies in seismic wave monitoring, like Rayleigh waves, and other indicators will be crucial to preventing disasters related to potential volcanic eruptions and associated tsunamis.

Image | NASA’s Earth Observatory

Related | Researchers Have Found 150,000 Tons of Ice on Mars Hidden in Plain Sight: In Its Volcanoes